Process and apparatus for producing steam by indirect heating



Jan. 13, 1931. o. H. HARTMANN 3 PROCESS AND APPARATUS FOR PRODUCINGSTEAM BY INDIRECT HEATING Filed Sept. 29 1927' 3 Sheets-Sheet 1 INVENTQRJan. 13,1931. o. HARTMANN 1,783,520

PROCESS AND APPARATUS FOR PRODUCING STEAM BY INDIRECT HEATING FiledSept. 29,1927 3 Sheets-Sheet 2 ATTORNEYS Jan. 13, 1931. o. H. HARTMANN1,788,520

PROCESS AND APPARATUS FOR PRODUCING STEAM BY INDIRECT HEATING FiledSept. 29, 1927 3 Sheets-Sheet 3 N 8 o v: mmMM NT R wkjm H [M A PatentedJan. 13, 1931 UNITED STA ornro H. HARTMANN, or cAssEL wILHE msnonE,GERMANY; assrcnon T0 or CASSEL-WILHELMSHOHE, GERMANY, A

SGHMIDTSCHE HEISSDAMPF G. M. B. H.,

CORPORATION OF GERMANY PROCESS AND APPARATUS FOR PRODUCING-STEAM BYINDIRECT HEATING Application filed September 29, 1927, Serial No.222,905, and in Germany January 31, 1923.

My invention relates to the generation of live steam, and particularlyof high-pressure steam, (that is to say, 20 atmospheres and over)withthe aid of a heating medium receiving heat from the combustion gasesand transferring such heat to the water to beconverted into steam, suchheating medium being circulated in a continuous closed path. Accordingto my present invention, the'heat of the furnace is transmitted to thewater to be converted into steam with the aid ofthe vapor of theheating'medium, andthe generation ofthe vapor, suchas steam"when wateris employed as'the heating medium,-is preferably conductedin'at leasttwo successive stages. The water (or other heatingmedium) to'beconverted into the steam constituting the heating medium is first heatedin a portion of the apparatus exposed to thecombustion gases which havepreviously come in contact with a vaporizing portion in which the waterthus previously heated is converted into the steam forming the heatingmedium for the generation ofsteam in the main boiler. With my inventionthe entire boiler plant may be made of relatively small dimensions. Thesteam, or other vapor serving as the heating medium, will circulatewithout in terruption in a closed path. The boiler proper containing thewater from which'the live steam is to be produced may be arranged insuch a manner as not to be exposed to the injurious effect of thecombustion gases. Owing to the subdivision of the generation of theheating medium into two stages,to wit pre-heating and vaporization, averyefiicient utilizatlon' of the heat of the combust onv Thearrangement of gases is obtainable. parts and the path of the combustiongases are such that the plant will readily admit of the inclusion of asuperheater which may beshutofi when desired. A very important advantageof my present invention resides in the fact that it affords anabsolutelysafe boiler plant for the production of high-pressure steam. The heatingmediumcirculates in narrow systems ofpiping which may be either sinuous,or coiled, or straight, and which contain a relatively small amount ofwater or other heating medium, thereby'pracis to say, the provision ofan efficient and ing repaired. As colmpared with a certain existingdevice known to me,.the new arrangement or subdivision of thecirculation path has the advantage that all thesections of the path-which'form part of the same heater, of the vaporizer, of the devicevfor transferring the heat to the water of the main boiler, etc., areexposed uniformly to the heating or the cooling medium. Thus therestage, for instance all sections of the preis, as it were, a parallelconnection of the 7 several sections of the same stage}. Additionaldevlces or arrangements serve for the more efficient carrylng outofthe 1nvent1on and thus enable it to accomplish more completely thepurpose which I have in view, that safe boiler plant for the productionof highpressure steam with the aid of indirect heat"- ing. Of course,thesteam' which serves as aheating medium-must be of a highertemperature than that of the live steam produced in the main boiler.Since it is well known that the temperature of saturated steamis ajfunctionof its pressure, it follows that the heating. steam, when wateris employed as the heating medium, must be under apressure exceedingthat'o'f thelive steam produced in the main boiler; i

for the circulation of heating steam are rela- I tively narrow andcontain but a small amount of water, the generation of the heating steamby intensive boiling in the vaporizer section of said path, wlth theresult that acertain z-proportion of water. will be carried along by ferof'heat fromt-he heat carrier or heating I '7 medium to the water in themain boiler will be much less 'eflicient'than if theheat carrier i Sincethe conduit-s forming the closed path in theclosed path is liable to beaccompanied v by removing from the'steam serving as heat carrier, anywater containedtherein before such steam reaches the heat transferringsurfaces located in the main boiler. This separation of water from thesteam before the lattenis brought in contact with the heat transferringsurfaces may be'accomplish'e'd' in various ways. w According to onespecies of my invention, a separator may be located at a proper point ofthe circulation path to remove such-water from the steam. Another modeconsists in subjecting the heating steam to the action of the heatinggases for such a length "of time that the heating steam'will V be ina'drytcondition at the time-it reaches the heat: transferring surfacesof the. main boiler. When employing the first of these procedures, .itis desirable to return the separated water to asuitable point'of thecirculation path ofthe heating steam. Thiswill promote the circulationofthe water andwill insure a thorough cooling of the heatingsurfaceexposed to the action of the combustion gases. Another advantage of thisarrangement is that on'lyarelatively small amount of water will berequired to-flow in this case in the preheating portion of thecirculation path which forms the first-step in the heating process, i.e. in the pre-heater, the amount of water being just as muchas isrequired. for the generation ofthe' heating steam, for, as

stated above, any water carriedover during f the generation of suchheating steam, is separated before it reaches the heat transfer devicein the main-boiler and is returned to the circulation system.,Tgheutemperature' of the condensate "flowing back to this preheater isreduced correspondingly andthe heat of the combustion gases isutilizedvery efiiciently. If, for instance, in theivaporizer portion of theheating system, boiling should be so violent as tocause the heatingsteam to carry along about-three times its weight of water, then, if thepresent invent-ion were not used, the weight of the water flowingthrough the preheater of the circulating system would be four times asgreat as the weight of water converted intosteam thevaporizer. Theamount (weight); of water necessary for the generation of the gaseousheat-carrier (the heating steam) would therefore be heated in thepreheater through a range of temperature only one-fourthof that existingduring normal working, that iswhen the amount of I water reaching thevaporizer of the heating steam (gaseousheat-carrier) is just sufficientfor the production of such heating steam, and

eliminated from the heating steam before such steam reaches the heattransferring surfacesin the main boiler, the effiiencj of the boilerplant is'increased considerably. A further advantage is that thepressure required for the circulation isreduced, since the velocity ofthe water is diminished in those parts 'of the circulation path whichare exposed to the furnace gases, whereby the a resistance to the flowis decreased. Thiscase is a continuation in part of appli- .er: and{embodied in my present invention. F g. 21s across-sectionsubstantiallyon line 22 of-hEig. 1. Figs. 3 and 5 are views similar to-Fg. 1;illustrating twofurther embodiments ofmy invention. Fig. 4 is aver- '95 tical section substantially on. line 4- 4 of Fig. 3 Flg. 6 1s aplan viewof the vaporizer shown in Fig. 5, andF1g-7 is .a diagraimnatic.elevatiom'with parts insection, showing still ,another. boiler plantembodying my invention. Figs. 8 and 9 are vertical sections of asomewhat diagrammatic character illustrating two furthermodifications'of my pres ent invent-ion provided with a separator.

Inthe'construction shown in Figs. 1' and 2, the. combustion'gases travelfirst through the flue-like portion or compartment .A.adjaquentlythrough the compartment B. The hottest portion of thecombustion gases is I 'thusbrought-into contact with the vaporizer.

C located in the compartment A and consisting of suitable tubing, theinlet of which, locateda't the lower portion of the vaporizer, isconnected'by a pipe 5 with the outlet located at'the upper end of thepre-heater D located in compartment "B. It will be understood that themedium employednfor heating the steam in the main boiler E passes into.the

.cations'Serial No. 678,561, filed December 5. 1923, and Serial 'NO.708,122, filed April 22,

cent to, the burner or furnace 14 and subsepre-heater D at the lower endthereof so that said medium (generally water) is heated, but usually nottothe boiling point. The medium thus pre-heated thenpasses throughthepipe 5 to the vaporizer C in which it is converted into vapor orsteanr by the heat of'th'e hottestportion of the combustion gases.Theboiler proper E islocated above the path of-the combustion' gases andispreferably protected by'a wall 15 against contact'with such gases andagainst the direct radiation of heat from the furnace. If the mainboilerE were heated directly by the combustion gases, there would be anaccumulation of heat in those parts of the boiler-shell exposed to suchcombustion gasesand there would result considerable temperature strainswhich, in boilers for the production of high-pressure steam, would soonsubject the material of the boiler-shell to excessive fatigue, thusimpairing its strength and rendering the boiler unserviceable after arelatively short time. From the vaporizer C a conduit, or setofconduits, 16 leads to a set of pipes 13 locatedwithin the water spaceof the main boilerE. The outlets of these pipes are connected with theinlet of the preheater -D by means of a conduit 1. It will thus be seenthat a complete or continuous circulation path is provided for themedium which, at one portion of such path, ,takesup heat from thecombustion gases and at another portion of the same path transfers suchabsorbed heat to the water contained in the main boiler E. Preferablythe vaporizer C,

as well as the pre-heaterD and the pipe 'sys-. tem 13, consist ofseveralsections asindi'c'ated in Fig. 2, connected with each other inany suitable manner. Owing to this arrangement 'defective or injuredparts of the pre-heater,

of the vaporizer, or of the heat-transferring pipes, may be removed andreplaced readily. Fig. 2 shows each of the said successive por- "ti'onsmade in three sections; and it will be obvious from thedrawing that eachof the "sections of the same stage of the apparatus is exposed equallyto the medium which is in contact with the outer surfaces of suchsections. The individual sections of the same portion of thecircuit are,as it were, connected in parallel, that is to say, not in series. Therefore, if any section should become defective the operation may becontinued temporarily with theremaining sections alone. Above the mainboiler E is shown a steam collector or drum 8 receivmg steam from said:boiler through a serles of short pipes From the steam collector 8 aconduit 9 leads tothe superheater 10 which is located'in the upperportion of the compartment B. By arranging the pre-heater D in the lowerportionof the compartment B where/the combustionorhelicalconstruction.This'portio'n of the plant may then be utilized as a heater forfeed-water on its way to the boiler, saidfeed water enteringthecontainer, or containers, 3

at the bottom through a pipe 4 and passing 'from the top ofthecontainertlirough a pipe etc to the boiler E. The heating mediumcirculating through the path described becomes ,thermo-siphon principle.

cooled in the container 3 as itgives ofl its heat to the feed-water, andas the heating medium" thus becomes condensed, and consequently heavier,its circulation is improved on the The hot gases, after travelingthrough the compartment A, may be directedby the dampers 17, either tothe upper end of the compartment B, or to the lower portion of saidcompartment, through the flue 6. The superheater '10 may thus be.

out oif from the heating circuit when desired. The entire plant is ofvery efficient and .certain operation, that is to say, it does notreadily get out of order, these advantages being obtained largely by thearrangement described for promoting the circulation of the heatingmedium and for sub-dividing the pre-heater, the vaporizer, etc.

It will be understood that Figs. 1 and 2 I illustrate but one example ofa plant embody ing my invention and that various other constructions maybe-adopted. Thus in Figs.i8 andp l I haveyi'llustrated a boiler plant inwhich the prerheater Dv ,(of asinuous shape similarto that showninFig. 1) supplies-the pie-heated water through pipe 5 to the upper header180i the'vaporizer C which also comprises upright pipes 19 connectedwith the lower, header 18. The water coming from the pipe will traveldownward in the pipes 19 so as to become heated and vaporized by the hotcombustion gases, while thesteam thus generated will pass upwardly toflow into the pipe 16 and thus reach theheating pipes 13 located withinthe main boiler E. The

cool water tendsto travel to the bottom of the pipes 19, while theheated water, being lighter than cool water, tends to rise in saidpipes. The heating medium therefore cir+ cula-tes automatically withinthe vaporizer C in substantially the same manner as the water in anordinary steam boiler. At the lowermost portion of the compartment B Ihave indicated a heat exchange apparatus 20for preheating the air on itsway to the boiler fur nace.

In Figs. 5 and 6 there is'represented a va- :porizer of such a shape andconstruction that 1t ,will practically fillthe cross-section of thecompartment A and thus insure a very eiiicient utilization of the heatcontained in the combustion gases. This vaporizer C2 is sub dividedintothree superposed sections 01, 02, 03, each having at its upper .end anoutlet connected with the respectivepipe 13 located in the water spaceof the boiler E, and at its lower end anv inlet connected with thepreheater which i's'not illustrated but maybe under'stood as being ofthe same character as thoze previously described injthis specification.From the "pipes .13 conduits 1 with feed-water heating portions '11 leadto the i n lets of the portions of the pre-heater in sub stantially thesame manner. as described above. In this construction alsothere will bea pluralityofseparate and independent "paths or, circuits for thecirculation: of'the heating medium; V

"According to Fig. 7 the vaporizer Chis con- Stl'lilCttIl as a fire box,directly aboye the turnace or grate 11. Like.theivaporizer ofFigs.

struction shown in Fig. 7..is particularly adapted for use in connectionwith portable boiler plants, for instance tractors, and the It will benoted that the water resulting from the condensation of. steam in theheating pipes 13 is cooled (specifically in the pipes 11) at aportion'of its returnpath-which lies at a higher level than the lowermost pointof the circulation path, and particularly at a level above thatofthe'inlet to the' heat receiving portion of said'path; Thus the coolwater will, owing-to the increase of its specific'gravity, sink to thelowermost portion of the circulation path, thereby not only promotingthe circulation, butinsurin that it shall take u l place in the properdirection. r

In 'F1gsr8 and- 9, X indicates a burner or a grate furnace from whichcombustion gases pass first upwardly through a chamber "A and thendownwardly through a chamber 1}, suitable dampersindicated at Y Y beingprovidedso that the combustion gases from the chamber Amay pass eitherto the upper onto the middleportion'ofthe chamber B,

depending upon whether it is desired to utilize only the heater locatedin the lower portion of the chamber B or also the superheate'r arrangedin the upper portion of said chamber B: When the superheater is'cut ofifrom th'e heating circuit, the position of the dampers Y, Y is asindicated inthe drawing, the combustion gases passingfi'rst' through'thefiuolike portion or compartment immediately above the furnace X, thenthrough chamber new open dalnperY. and throughjthe'nar row passagebetween the two chambers, into the lower portion of chamber B and overthe coils of the heater D to the fiue,througl1 the outlet belowsaid'hea'ter. hen it is desired to utilize the superheaterlocated in theupper portion of chamber B, the position cf the dampers is reversed fromthat shown in-the drawing, the damper Y being closed and Y being opened,the combustion gases thenpassing-froin chamber 1h,.i3l11011l1 damperQY"into chamber 7 B and downwardly over the coils oitthe superheater andheater D, :out to the stack. In these two chambers are arranged theparts constituting'the pre-heater tion of the chamber B, this heaterbeing in the-lorlnof a coil, theupper end otwhioh'is ccmnectedwiththevaporizer C located in the 3 chamber A. The outlet of they vaporizerconnected-by a-p1pe-102 with a separator103 in which-any of the liquidheating. medium, such. as water carried along by the vapor or. s eam isdeposited, While the steam ,froni -whichi #:he'water has thus beeneliminated passes through a pipe 104 to heat exchangesurtaces,-forinstance,-a pipe 106'l0cated within thewvater spacejof themain boiler E. The outlet 112 of the heat-transferring device or, ;pipe1 06 has a return' connection-101 leading tothelowe-r portion oftheheater D; return; connection may be ,itormed with a coil 1 01' forheatingthe feed'water for the' main boiler E, in a chamber'cor container109 having a water supply pipe 110 and a discharge pipe 111. The watercol'lecting in the. sepa-v rater 103 is returned to the circulation paththrough a; pipe. 105 preferably to the: lower end of the vaporizer CJThe upper end 113 otthe return pipe .105 connected tothsepaandthe-vaporizer for-the heating medium. 'The pre-heater Dis-located in the-lower porrator.-103 lies a considerable distance belowthe outlet-1120f; the heating element 106. As i a result of thisdifference inheight, the water surface in the return connectionlOl cannever rise so high that it reaches the outlet 1120i the heating element106 Iliere isftliusgals. aways present adefinitedrop which insures areliable: andrapid discharge of the conden-.

sate from the heating element. .Tliis condir f vtion is highly.important forthe proper func .tioning: of the..indirectly'heated boilerE be causea collectionof condensate in the heating element would. veryunfavorably affect the heat transfer from the heating element-106 to thecontents of the live'steam boilerE. By 1 means or' the above describedarrangementof' theseparator1103 and particularly ofits ter outlet 113and return pipe 105 with rela ti'ontothe outlet 112 of theheatingelement1-06, it'is insured thatthe passageways for the heating steam in theheating element are constantlymaintained free and open so that thetransfer ofheatnecessary for an. efiicient production ofghigh pressurelive steam can take place through thewalls of the heating element. At ZI have indicated ,a supe'rheat ing. coil located in the upperportionlof'the' chamber B, said; coilreceiving steam from the .mainboiler E and delivering said steam to theplace of use, for instance asteam engine.

lln the construction illustrated Fig.9,

thesteam constituting the heat carrieris Pro? duced by the combustiongasesimafirebo r F. The upper end of the steam generatinglcoil isconnected by a pipe 107 with a separator 103 of the same character as inFig. .8, the upper end of the separator having a. connection 104 forcarryingthe dry steam tothe heat transferring device 10?}.gThewaterwhich collects job 101 to the producer in which a mixture ofwater and steam is generated.

Various changes in the specific form shown and described may be madewithin the scope. of the claims without departing from the spirit of myinvention.

I claim:

l. A steam generating plant, comprising a boiler having a steam spaceand a water space, a heating pipe in the water space of the boiler, asubstantially tubular vaporizer the outlet of which is connected withthe inlet of said heating pipe, a substantially tubular liquid-heaterthe outlet of which is connected with the inlet of said vaporizer, abody of liquid in said vaporizer and liquid-heater of less volume thanthe combined volume thereof, a return connection from the outlet of saidheating pipe to the inlet of said liq uid-heater to complete the pathforthe circulation of said liquid and its vapors, a super heaterconnected with the steam space of said boiler, a conduit for conveyinghot gases into contact first with said vaporizer, then with thesuperheater, and subsequently with the said liquid-heater, a by-passthrough which said hot gases may travel from the vaporizer directly tothe liquid-heater without coming in contact with the superheater, and acon trolling device for directing the hot gases either through saidconduit or through said by-pass. v

2. A steam generating plant, comprising a boiler having a steam spaceand a water space, a heating pipe in the water space of the boiler, asubstantially tubular vaporizer the outlet of which is connected withthe inlet of said heating pipe, a separator interposed between saidoutlet and inlet, a substantially tubular liquid-heater the outlet ofwhich is connected with the inlet of'said vaporizer, a body of liquid insaid vaporizer and liquidheater of less volume than the combinedvolporizer directly to the liquid-heater without coming in contact withthe superheater, and

a controlling device for directing the hot gases; either through saidconduit or through said by-pass.

steam generating plant, comprisingfaboiler having a steam space and awater space, a substantially tubular heat transfer device in the waterspace of the boiler, a liquid vaporizer partially filled with a liquid,a furnace for heating said vaporizer, the outlet of the vaporizer beingconnected With the inlet of said heat transfer device, a separatorinterposed between said outlet and inlet, and located out of the path ofthe hot gases of the furnace, a return connection from the outlet ofsaid heat transfer device to the inof the vaporizer heating space of'thefurnace, to complete the path for the circulation of said liquid and itsvapors, and a return pipe leading from said separator to the lower endof said vaporizer, and locatedmainly externally of the vaporizer heatingspace of the furnace, the inlet of said return pipe being situated at alevel lower than that of the outlet of the said heat transfer device,and the body of liquid in such vaporizer being of such-quantity that,when the plant is in operation, the heat transmitting medium deliveredfrom the vaporizer to the tubular heat transfer device consistssubstantially of the vapor of such liquid.

i. The process of generating live steam which comprises causing hotgases to give ofi their heat to a substance which is liquid under theconditions of operation and convert such liquid into wet high pressurevapor, drying such vapor by separating the entrained liquid therefromand returning such liquid, by apath different from the path of such wetvapor, to the body of liquid heated by said gases, bringing the vaporthus produced into heat exchange relationto a separate body of water tobe converted into live steam of a pressure lower than that of saidvapor, the latter giving up its heat to such separate body of water andcondensing, and bringing the liquid resulting from the condensation ofsaid vapor back into heat exchange relation with said hot gases.

ume thereof, a return connection from the 4 outlet of said heating pipeto the inlet of of said boiler, a conduit for conveying hot gases intocontact first with said vaporizer,

then with the superheater, and subsequently with the said liquid-heater,a by-p ass through. V

. let off said vaporizer and located externally

